Drugs and the Nervous System

Drug: Any substance, other than food, that changes

the structure or function of the body

ALL drugs (prescription, over the counter and illegal) have potential to do harm if abused or used improperly.

Drugs differ in ways they affect the body. (kill bacteria, treat disease, affect particular body system)

Some of most powerful drugs cause changes in the Nervous System (within brain and at synapses between neurons)

Drugs That Affect the Synapse

Synapse: Key relay station in transmission of information within N.S.

Neurotransmitters: transmit messages between neurons or neuron and effector. Drugs that interfere with actions of neurotransmitters can disrupt the N.S for better (treatment of disease) or worse (abused or misused.

Stimulants: Increase actions regulated by N.S (Ex. increase heart rate, blood pressure, breathing) and increase release of neurotransmitters at some synapses in the brain feeling of energy and well being.

Effects of stimulants wear off brain’s neurotransmitters depleted.

User suffers fatigue & depression

Long term use circulatory problems, hallucinations, depression

Depressants: Decrease rate of functions regulated by the brain

(Ex. decrease heart rate, blood pressure, breathing, relax muscles and relieve tension, anxiety).

Some depressants enhance effects of neurotransmitters that prevent start of action potentials. (exhititory/inhibitory compete)

Combination of depressants and alcohol can depress CNS until breathing stops fatal

Types of Drugs

Cocaine

Opiates

Marijuana

Alcohol

Cocaine: Causes the sudden release in brain of neurotransmitter dopamine which leads to intense feelings of satisfaction & pleasure.

Supply of dopamine depleted when drug wears off depression dependence on cocaine

Cocaine: stimulant that increases heart rate & blood pressure. Can lead to heart damage or heart attack

Crack cocaine: potent form of cocaine, highly addictive because intense high wears off fast.

Cocaine comes from the South American Coca plant

Opiates: Mimic endorphins, natural chemicals in the brain that help to overcome sensations of pain.

1st doses strong feelings of pleasure but body quickly adjusts to higher levels of endorphins. Result, body can’t do without the drug.

When user stops uncontrollable pain & sickness because the body can’t produce enough endorphins.

Marijuana: most widely used illegal drug from Cannabis sativa (a species of hemp plant).

Hashish (Hash): potent form of marijuana from flowering parts of the plant.

THC: (Tetrahydrocannabinol) Active Ingredient

Produces temporary feeling of euphoria and disorientation.

Worse than smoking tobacco for the lungsLong term use may memory loss, inability to concentrate, decreased testosterone in males.

Alcohol: Depressant that slows down the rate of CNS function.

Slows down reflexes, disrupts coordination, impairs judgment.

Pregnant women who drink on a regular basis risk having a child with Fetal Alcohol Syndrome (FAS), a group in birth defects caused by effects of alcohol on the fetus.

FAS babies can suffer heart defects, malformed faces, delayed growth, poor motor development.

In US >50,000 babies born/year with alcohol related birth defects, many which are irreversible.

Long term alcohol abuse destroys liver cells where alcohol is broken down.

Scar tissue develops (cirrhosis) which eventually blocks flow of blood through the liver & interferes with liver functions.

Eventually death may occur from liver failure.

Liver with cirrhosis increases in size due to build up of scar tissue

Drug Type Medical Use Examples Effects on Body

Stimulants Increase alertness, relieve fatigue

Amphetamines Inc. heart & resp. rates, elevates BP, dilates pupils, dec. appetite

Depressants Relieve anxiety, irritability, tension

BarbituatesTranquelizers

Slows actions of CNS. Sm amtscalm, relaxLg amtsslurred speech, impaired judgement

Opiates Relieve pain MorphineCodeine

Depressant. drowsy, restless, nausea

Commonly Abused Drugs